Fired heater

ABSTRACT

1,129,076. Fluid heaters. FOSTER WHEELER CORP. 28 April, 1966 [11 June, 1965], No. 18729/66. Headings F4A and F4S. A process fluid heater has rows of vertical tubes 41 extending through an enclosure 21 into which burners 31 fire, the gases from the enclosure 21 then passing over convection heated tubes 27. The tubes 41 are supported by a weight and pulley arrangement 49 from frame 53, and are supplied with fluid from upper header 50 through connectors 58, 60. The tubes 41 are provided with removable end caps 47, through which catalyst (54, Fig. 5) and catalyst support cones (51) may be inserted. From the tubes 41, the fluid passes through connectors 55 to a horizontally extending lower collector header 42, which is mounted in a support casting 44 by a bracket and slot arrangement (48, 46, Fig. 2) to permit longitudinal expansion of the header. A metal bar 61, having expansion rate similar to that of the header 42 is placed parallel thereto in contact with and between the tubes 41, a little above the point of connection of the connectors 55 to the tubes. This expands as the header does, thereby bowing out the tubes 41 at their lower end, and preventing the connectors 55 from breaking. The bar is formed from a plurality of half sections 63, Fig. 3, each section engaging four of the tubes, the sections being bolted together at their edges. The sections associated with each row of tubes, are cross linked by members 73, to form the bar 61 which is maintained in place by spaced lugs (77, Fig. 2) on the tubes. In a modification (Figs. 5 to 8) provided with a single row of vertical tubes, the bar (61) is formed from two overlapping half bar sections (81).

g- 23, 1955 K. A. DE GHETTO ETAL 3,267,915

FIRED HEATER Filed June 11, 1965 3 Sheets-Sheet 1 Irv vE/v TUQS K. H.175 EHETTU LU. LUNG [Z KHHTS/UE' SH/H-PHL/N HE H J-ZTTUQNEQ Aug. 23, 1966 K. A. DE GHETTO ETAL 3,267,915

FIRED HEATER 5 Sheets-Sheet :3

Filed June 11, 1965 n WW n m w a m W531 H g- 23, 1966 K. A. DE GHETTO ETAL 3,267,915

FIRED HEATER 5 Sheets-Sheet 5 Filed June 11, 1965 United States Patent Chester, and George Kratsios, Verona, N.J., and Shih- Yaun Yeh, Bronx, N.Y., assignors to Foster Wheeler Corporation, New York, N.Y., a corporation of New York Filed June 11, 1965, Ser. No. 463,211 6 Claims. (Cl. 122-510) This invention relates to fired heaters and more particularly to apparatus for use in fired heaters for improving the construction of tube to header connections.

In fired heaters, particularly those in which rows of tubes are placed in a vertical plane within the heater enclosure, it has long been recognized that expansion of the outlet header results in severe stresses in the connectors between the header and the fired heater tubes. In the past, to compensate for the horizontal expansion of the header and still connect the vertical tubes to the header, large loops or pigtails were used. These loops have suflicient length so that they were adequately flexible to permit the horizontal header to expand while the vertical tubes within the fired heater remained fixed at least in the direction of expansion of the horizontal header.

Therefore, it is an object of this invention to provide a fired heater of improved and more economical construction.

Another object is to provide a fired heater having a tube to header connection of more economical and improved construction.

In accordance with this invention, an enclosure provides a chamber into which hot gases and flame are injected by burners projecting into the chamber through the enclosure. Vertical tubes are suspended within the chamber and extend slightly beneath the bottom of the chamber. Connectors extend from the sides of the tubes at a point a short distance above their lower ends directly to the header. Above the point of intersection with the connectors, but in its general vicinity is a horizontal bar which is in contact with the tubes and expands at a rate approximately equal to the thermal expansion rate of the header thereby bowing the vertical tubes apart and eliminating the stress of the connectors caused by the thermal expansion of the header.

The invention may he better understood from the following detailed description considered in conjunction with the accompanying drawings in which:

FIGURE 1 is a side elevation partially in cross section of a fired heater utilizing the invention and having a double row of tubes.

FIGURE 2 is an enlarged view of the lower portion of FIGURE 1.

FIGURE 3 is a' cross-sectional view taken along line 3-3 of FIGURE 2.

FIGURE 4 is a cross-sectional view taken along line 4 4 of FIGURE 2.

FIGURE 5 is a view similar to FIGURE 2 of a fired heater utilizing the invention and having a single row of tubes.

FIGURE 6 is a cross-sectional view taken along line 6-6 of FIGURE 5.

FIGURE 7 is a cross-sectional view taken along line 77 of FIGURE 6.

FIGURE 8 is a cross-sectional view taken along line 88 of FIGURE 6.

Referring now to the drawings and more particularly to FIGURES-1 and 2, an enclosure 21 forms a chamber 23. The enclosure 21 is formed of multilayers of insulating and structural material. Extending upward from the chamber 23 is a convection compartment 25 in which atmosphere.

3,267,915 Patented August 23, 1966 convection tubes 27 are located. Through the enclosure 21 are ports 29 which permit burners 31 to provide flame and hot gases within the chamber 23, which pass upward through the convection compartment 25 and out to the Located along a vertical centerline of the chamber 23 is an arch opening 33. Directly beneath the arch opening 33 is a bottom opening 35. Extending downward from the bottom opening is a lower extension 37. A side extension 39 of irregular shape forms a header space 40 to one side of the lower extension 37.

Extending from slightly above the arch opening 33 to below the lower end of the lower extension 37 are tubes 41 which are vertically oriented. The tubes 41 are placed in FIGURES 1 and 2 along two rows; namely, a first row 43 and a second row 45. In FIGURE 5 only one row of tubes 41 is utilized. A lower header 42 is located within the header space 40 with its longitudinal axis disposed horizontally at approximately right angles to the longitudinal axis of the tubes 41. The header is mounted on a support casting 44 which has a longitudinal groove 46 therein. A bracket 48 extending from the header 42 fits into the groove 46 thereby permitting longitudinal expansion of the header 42. The upper and lower ends of all the tubes 41 have removable caps 47 connected to them. The caps 47 are required to insert and remove catalyst 48 (FIGURE 5) from within the tubes. Catalyst support cones 51 are located at the lower end within each tube 41 to support, as their name implies, the catalyst 48 within the tubes 41.

The tubes 41 are shown supported by a weight and pulley arrangement 49 but other equipment such as springs or a fulcrum are also applicable. The weight and pulley arrangement 48 is supported by a structural frame 53 which also supports the entire unit including the enclosure 21 and convection compartment 25.

Connectors 55 extend directly along the shortest distance between the tubes 41 and the lower header 42. The connectors 55 as shown in FIGURES l and 2 include first connectors 57 which join the first row of tubes 43 with the lower header 42 and second connectors 59 which join the second row of tubes 45 with the lower header 42. Prior to this invention, the connectors 55 would have had to be extremely long and looped down from the tubes 41 and back up to the header 42. This is because, in operation, the lower header 42 expands horizontally thus requiring the connectors between the tubes 41 and the header 42 to be flexible.

An upper header 50 supported by a flexible assembly such as a spring (not shown) supplies the fluid to be heated through upper connectors 56 to the tubes 41 near their upper ends. Where more than one row of tubes 41 are used, the upper connectors 56 include first connectors 58 to join the first row of tubes 43 near their upper ends with the upper header 50 and second connectors 60 to join the second row of tubes 45 near their upper ends with the upper header 50. Since the connectors 56 are sufliciently flexible to accommodate the thermal expansion of the header 50, growth of the tubes 41 along their longitudinal axis is'compensated for by the upward movement permitted by the weight and pulley arrangement 48 and the flexible assembly which supports the header 50.

In accordance with this invention, a metallic bar 61, having an expansion rate similar to the header 42 is placed in contact with and between the tubes 41 a short distance above the point where the leads 55 connect with the tubes 41. As best seen in FIGURE 3, for a double row installation the bar 61 is formed of sections 63 each having, for example, four indentations 65 therein. A ridge 66 is located along the edge of the sections 63 opposite the indentations 65. The indentations 65 are shaped to fit about slightly more than half the cross-sectional area of the tubes 41. The sections 63 are fitted end on end and secured together by bolts 67. In this way, a first halt-bar 69 and a second half-bar 71 are formed. The first half-bar 69 is fastened to the second half-bar 71 by linking members '73. The linking members 73 are secured to the sections 63 by pins 75. Pairs of lugs 77 (FIGURE 2) are secured to selected tubes, preferably the tube at each end of a section 63. The ridge 66 sets between each pair of lugs 77. Thus, as the header 42 expands, the bar 61 also expands causing the lower ends of the tubes 41 to move in the direction of the expension of header 42. Also, as the connectors 75 expand along their longitudinal axis, the lower ends of the tubes 42 move at approximately ninety degrees to the movement caused by the expansion bar. In this way, the header 42 can expand as required without breaking the connectors 55 and without excessive material being used to form the connectors 55. As shown in FIGURE 4, rods 80 welded to the structural frame 53 serve to secure the tubes 41 in the center of their respective row to prevent expansion taking place in only one direction and cause the expansion to be in both directions from the center tubes. Lugs 82 are secured to the tubes 41, but only rest on the frame 53 to prevent vertical movement downward.

As best seen in FIGURES through 8, where only a single row of tubes is utilized within a fired heater, a different arrangement for the bar 61 is used. Bar sections 81 having indentations 83 located in flat plate or web portions 84, are placed about the tubes so that the edges of the web portions 84 of the sections 81 overlap. Pins 85 are placed through holes 87 in the overlapping webs 84-. The pins 85 are retained in place by lengths of wire 89 fitted through an opening provided in each pin 85 and then bent. Bolts 91 extending through extensions 93 on the webs 84 connect the sections 81 end to end. The sections 81 have outside edge ridges 95 and inside web ridges 97 to add structural strength to the sections 81. Lugs 99 are located on both sides of every other tube and fit into openings 100 in the sections 81 to support the bar 61.

In order to prevent the bar 81 from expanding only in one direction along the row of the tubes, the two center tubes in the row, as shown in FIGURE 8, are welded to rods 121 which are welded at their opposite ends to the structural frame 73.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A fired heater comprising:

an enclosure forming a chamber;

means for supplying hot gases to said chamber;

a row of tubes located in a common plane within said chamber, the longitudinal axis of each tube being parallel to the longitudinal axis of the other tubes;

means for supplying fluid into said tubes near one end of said tubes;

a header located in a plane parallel to said plane of said row of tubes and having its longitudinal axis at approximately right angles to the longitudinal axis of said tubes;

connectors extending directly from near the ends of said tubes opposite from the ends for supplying fluid into said header; I

a bar parallel to said header in contact with each tube in said row of tubes and having a rate of thermal expansion approximately similar to said header whereby said tubes are spread apart by the thermal expansion of said bar as said header thermally expands preventing the breaking of said connectors by the thermal expansion of the header; and

means for retaining said bar in contact with said tubes.

2. A fired heater comprising:

an enclosure forming a chamber;

means for supplying hot gases to said chamber;

a row of tubes vertically suspended within said chamher, said row having a common plane; 4

means for supplying fluid into the upper portion of said tubes;

a header located adjacent the lower ends of said tubes,

the longitudinal axis of said header being at approximately right angles to the longitudinal axis of said tubes;

connectors extending directly from the lower portion of said tubes to said header;

a bar in contact with each tube in said row of vertical tubes with its longitudinal axis at approximately right angles to the longitudinal axis of said tubes and having a rate of thermal expansion approximately equal to said header whereby said tubes are spread apart by the thermal expansion of said horizontal bar as said header thermally expands preventing the breaking of said connectors by the thermal expansion of the header; and

means for retaining said horizontal bar in contact with said tubes.

3. A fired heater comprising:

an enclosure forming a chamber;

means for supplying hot gases to said chamber;

two rows of tubes vertically suspended Within said chamber, each row being in a common plane and both planes being parallel to one another;

means for supplying fluid into the upper portion of said tubes;

a header located adjacent the lower ends of said tubes, the longitudinal axis of said header being at approxi mately right angles to the longitudinal axis of said tubes;

connectors extending directly from the lower portion of said tubes to said header;

a pair of bars each in contact with the tube in a separate row of said two rows of vertical tubes with their longitudinal axis at approximately right angles to the longitudinal axis of said tubes and having a rate of thermal expansion approximately equal to said header whereby said tubes are spread apart by the thermal expansion of said horizontal bars as said header thermally expands thereby preventing the breaking of said connectors by the thermal expansion of the header; and

means for retaining said horizontal bars in contact with said tubes.

4. A fired heater according to claim 3 wherein each bar is formed in section having indentations in one edge of a configuration similar to the outside cross-sectional area of slightly more than half a tube.

5. A fired heater according to claim 4 wherein said means for retaining said bars in place includes lugs welded to said tubes.

6. A fired heater according to claim 4 wherein said means for retaining said bars in place includes lugs welded to said tubes and linking members extending from one bar to the other.

References Cited by the Examiner UNITED STATES PATENTS 3,062,197 11/1962 Fleischer 122-510 3,172,739 3/1965 Koniewiez 122-510 X 3,195,989 7/ 1965 Pyzel 122356 X KENNETH W. SPRAGUE, Primary Examiner. 

1. A FIRED HEATER COMPRISING: AN ENCLOSURE FORMING A CHAMBER; MEANS FOR SUPPLYING HOT GASES TO SAID CHAMBER; A ROW OF TUBES LOCATED IN A COMMON PLANE WITHIN SAID CHAMBER, THE LONGITUDINAL AXIS OF EACH TUBE BEING PARALLEL TO THE LONGITUDINAL AXIS OF THE OTHER TUBES; MEANS FOR SUPPLYING FLUID INTO SAID TUBES NEAR ONE END OF SAID TUBES; A HEADER LOCATED IN A PLANE PARALLEL TO SAID PLANE OF SAID ROW OF TUBES AND HAVING ITS LONGITUDINAL AXIS AT APPROXIMATELY RIGHT ANGLES TO THE LONGITUDINAL AXIS OF SAID TUBES; CONNECTORS EXTENDING DIRECTLY FROM NEAR THE ENDS OF SAID TUBES OPPOSITE FROM THE ENDS FOR SUPPLYING FLUID INTO SAID HEADER; A BAR PARALLEL TO SAID HEADER IN CONTACT WITH EACH TUBE IN SAID ROW OF TUBES AND HAVING A RATE OF THERMAL EXPANSION APPROXIMATELY SIMILAR TO SAID HEADER WHEREBY SAID TUBES ARE SPREAD APART BY THE THERMAL EXPANSION OF SAID BAR AS SAID HEADER THERMALLY EXPANDS PREVENTING THE BREAKING OF SAID CONNTORS BYY THE THERMAL EXPANSION OF THE HEADER; AND MEANS FOR RETAINING SAID BAR IN CONTACT WITH SAID TUBES. 